Currently, standards for a very high throughput Wireless Local Area Network (WLAN) are under consideration for inclusion in the IEEE Standard 802.11 VHT (very high throughput) Standard. One major difference between the type of WLAN being considered for standardization and other IEEE Standard 802.11x PHY (physical) layer architectures, such as those in IEEE Standard 802.11(n), is the introduction of Spatial Division Multiple Access (SDMA) and Orthogonal Frequency Division Multiple Access (OFDMA) in the WLAN communications.
As understood by one skilled in the art, SDMA and OFDMA can potentially create communication resource shortages. Therefore, a need exists for algorithms and mechanisms which allow for concurrent access of the same bandwidth by different users. However, the CSMA scheme, which is used in IEEE Standard 802.11x systems, does not provide a natural way for multiple users to share a common time slot. Hence, the current CSMA scheme is generally viewed as unsuitable for use in a VHT WLAN.
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